Color Hill-Shaded GeoTIFF Image Showing the 2-m bathymetry Generated from National Oceanic and Atmospheric Administration (NOAA) Survey H11252 in Eastern Long Island Sound (H11252_2MUTM18_MB.TIF, UTM Zone 18)

The U.S. Geological Survey, in cooperation with the National Oceanic and Atmospheric Administration and the Connecticut Department of Environmental Protection, has produced detailed geologic maps of the sea floor in Long Island Sound, a major East Coast estuary surrounded by the most densely populated region of the United States. These studies have built upon cooperative research with the State of Connecticut that was initiated in 1982. The current phase of this research program is directed toward studies of sea-floor sediment distribution, processes that control sediment distribution, nearshore environmental concerns, and the relation of benthic community structures to the sea-floor geology. Anthropogenic wastes, toxic chemicals, and changes in land-use patterns resulting from residential, commercial, and recreational development have stressed the environment of the Sound, causing degradation and potential loss of benthic habitats (Koppelman and others, 1976; Long Island Sound Study, 1994). Detailed maps of the sea floor are needed to help evaluate the extent of adverse impacts and to help manage resources wisely in the future. Therefore, in a continuing effort to better understand Long Island Sound, we have constructed and interpreted multibeam bathymetric data within specific areas of special interest. The color GeoTIFF of hill-shaded bathymetry in UTM Zone 18 projection presented herein covers a roughly 64 km square area of the sea floor in the area just west of Six Mile Reef, eastern Long Island Sound. The original multibeam bathymetric data were collected during 2004 as part of charting applications aboard the NOAA Survey Vessel Thomas Jefferson. A Simrad EM1002 multibeam system mounted on the hull of this vessel was used to acquire data along survey lines from the deeper water (>20 m) parts of the study area. Two 29-foot launches with hull-mounted Reson systems were deployed from the ship and were used to acquire data along survey lines from the shallower areas. Detailed bathymetric data and their interpretations serve many purposes, including: (1) defining the geological variability of the sea floor, which is one of the primary controls of benthic habitat diversity; (2) improving our understanding of the processes that control the distribution and transport of bottom sediments and the distribution of benthic habitats and associated infaunal community structures; and (3) providing a detailed framework for future research, monitoring, and management activities. The bathymetric data models also serve as base maps for subsequent sedimentological, geochemical, and biological observations, because precise information on environmental setting is important for selection of sampling sites and for accurate interpretation of point measurements.美国地质调查局（U.S. Geological Survey）与国家海洋和大气管理局（National Oceanic and Atmospheric Administration）、康涅狄格州环境保护部合作，针对美国东海岸的重要河口湾——长岛海湾（Long Island Sound）编制了详细的海底地质图。该海湾周边为全美人口最密集的区域，此项研究依托1982年启动的康涅狄格州合作研究项目开展。本研究计划的当前阶段，围绕四项主题展开：海底沉积物分布、调控沉积物分布的动力过程、近岸环境问题，以及底栖群落结构与海底地质的关联。 居住、商业及休闲开发引发的人为废弃物排放、有毒化学品污染与土地利用模式改变，已对长岛海湾的生态环境造成胁迫，导致底栖生境退化乃至潜在丧失（Koppelman等，1976；长岛海湾研究组，1994）。亟需高精度海底图件，以评估不利影响的波及范围，为未来的资源科学管理提供支撑。为此，为进一步深化对长岛海湾的科学认知，研究团队针对重点关注的特定区域，构建并解译了多波束测深数据。本文呈现的通用横轴墨卡托（UTM）18带投影下的晕渲水深彩色GeoTIFF影像，覆盖了长岛海湾东部六英里礁西侧约64平方千米的海底区域。原始多波束测深数据采集于2004年，搭载于NOAA“托马斯·杰斐逊”号测量船，用于海图制图作业。该船船体搭载的Simrad EM1002多波束系统，沿研究区水深大于20米的深水区域测线采集数据；研究团队同时从母船部署两艘29英尺工作艇，艇体搭载Reson声呐系统，用于采集浅水区的测线数据。 高精度水深数据及其解译成果具备多重应用价值：其一，明确海底地质异质性——这是调控底栖生境多样性的核心因素之一；其二，深化对底沉积物分布与输运过程、底栖生境及相关底内动物群落结构分布规律的认知；其三，为后续研究、监测与管理活动提供详细的基础框架。水深数据模型同时可作为后续沉积学、地球化学及生物学观测的底图，因为环境背景的精确信息对于采样点位遴选及点位测量结果的精准解译至关重要。